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Lesson 1-9Solving Addition &

Subtraction Equations

A. AB. BC. CD. D

A. –31

B. –11

C. 11

D. 31

Subtract –21 – (–10).

(over Lesson 1-5)

1. A2. B3. C4. D

A. –25

B. –13

C. –5

D. –1

Find the mean of the following set of integers. 3, –6, –8, –10, –4

(over Lesson 1-6)

A. AB. BC. CD. D

Write the verbal phrase half of Sylvia’s money as an algebraic expression.

(over Lesson 1-7)

A. 2 ● x

B.

C.

D. x – 2

1. A2. B3. C4. D

A. -15

B. -9

C. 15

D. –8

Evaluate the expression a + c + b if a = –3, b = –7, and c = –5.

(over Lesson 1-5)

1. A2. B3. C4. D

A. –5

B. 5

C. –1

D. 1

Evaluate the expression | a | – c -|b| if a = -1, b = -8, and c = –2.

(over Lesson 1-5)

1. A2. B3. C4. D

A. 0

B. 8

C. -4

D. -8

Evaluate – 4 –(-4) + (-4) - 4

(over Lesson 1-5)

• solve

• solution

• Solve equations using the Subtraction and Addition Properties of Equality.

• inverse operations

Finding the value of a variable to make the equation true.

The value of a variable.

The opposite operation that will “undo” the other. Subtraction will “undo” addition & addition will “undo” subtraction.

Reinforcement of Standard 6AF1.1 Write and solve one-step linear equations in one variable.

Solve an Addition Equation

Solve 7 = 15 + c.

Method 1 Vertical Method

7 = 15 + c

–8 = c

7 = 15 + c–15 –15

Write the equation.

Combine a -15 to each side to cancel out the 15, isolating the variable & finding its’ solution.

Solve an Addition Equation

Method 2 Horizontal Method

7 =15 + c

7 – 15 = 15 – 15 + c

–8 =c

Write the equation.

Combine a -15 to each side to cancel out the 15, isolating the variable & finding its’ solution.

Solve an Addition Equation

OCEANOGRAPHY At high tide, the top of a coral formation is 2 feet above the surface of the water. This represents a change of –6 feet from the height of the coral at low tide. Write and solve an equation to determine h, the height of the coral at low tide.

Words The height of the coral at low tide plus (–6) feet is 2 feet.

Variable Let h represent the height of the coral at low tide.

Equation h + (–6) = 2

Solve an Addition Equation

h + (–6) = 2

h + (–6) + 6 = 2 + 6

Answer: The height of the coral at low tide is 8 feet.

h = 8

Write the equation.

Combine a 6 to each side canceling out the -6, isolating the variable to find its’ solution.

Solve a Subtraction Equation

Solve –5 = z – 16

Method 1 Vertical Method

–5 =z – 16

–5 = z – 16

+16 +16

11 = z

Write the equation.

Combine a 16 to each side canceling out the -16, isolating the variable to find its’ solution.

Solve a Subtraction Equation

Method 2 Horizontal Method

–5 = z – 16

Answer: The solution is 11.

–5 + 16 = z – 16 + 16

11 = z

Write the equation.

Combine a 16 to each side canceling out the -16, isolating the variable to find its’ solution.

A. AB. BC. CD. D

A. –5

B. –3

C. 13

D. 17

Solve 6 = 11 + a

1. A2. B3. C4. D

A. $65

B. $45

C. $62

D. $32

If Carlos makes a withdrawal of $15 from his savings account, the amount in the account will be $47. Write and solve an equation to find the balance of the account before the withdrawal.

x -15 = 47

1. A2. B3. C4. D

A. –6

B. –3

C. 6

D. 9

Solve –6 = x –12

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